What is the Latissimus Dorsi? - Definition & Function

Instructor: Dan Washmuth

Dan has taught college Nutrition, Anatomy, Physiology, and Sports Nutrition courses and has a master's degree in Dietetics & Nutrition.

The latissimus dorsi is one of the widest muscles in the back, and is one that everyone uses each day of their life. Learn all about the definition and functions of the latissimus dorsi muscle in this lesson.

Latissimus Dorsi

Think all the way back to your early childhood. Did you ever play on the jungle gym during recess? Specifically on the monkey bars? Now think back to your high school gym class. Did you ever have to do pull-ups or chin-ups?

In any of these activities you were using your latissimus dorsi muscle, one of the widest muscles in the back.

Playing on the monkey bars requires the use of the latissimus dorsi muscles.
monkey bars

Latissimus Dorsi: Definition

The name of the latissimus dorsi muscle comes from the Latin words latissimus, which means 'broadest', and dorsum, which means 'back'. Therefore, latissimus dorsi simply means 'broadest muscle of the back.' Oftentimes, it's simply known as the 'lat' muscle.

Although the latissimus dorsi muscle is very broad, is it also quite thin. It's a triangular-shaped muscle located at each side of the back, under the arms. The latissimus dorsi muscle is partly covered by the trapezius muscle, which is another large muscle in the middle and upper back.

The latissimus dorsi muscle is a thin, wide, triangular-shaped muscle located at each side of the back, under each arm.
lat muscle

Some interesting facts about this muscle include:

  • The muscle fibers in the latissimus dorsi can be used when reconstructing breast tissue following a mastectomy (breast removal).
  • Sometimes muscle tissue from the latissimus dorsi is used to wrap around a weak heart during a cardiomyoplasty. A pacemaker is then inserted into the body to stimulate the transplanted muscle, which then squeezes the heart. This causes the heart to pump blood just like a healthy, strong heart.

Latissimus Dorsi: Function

Even though the latissimus dorsi is located in the back, the latissimus dorsi functions to move the arms. Specifically, this muscle functions to adduct, medially rotate, and extend the arms.

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